Upon contraction, the smallest motor unit, that is, the one associated with the fewest muscle fibers, is the normally the first activated. As the contraction progresses, larger motor units are brought into play.Efficient muscle contraction depends on the motor units within a muscle working effectively together.pon contraction, the smallest motor unit, that is, the one associated with the fewest muscle fibers, is the normally the first activated. As the contraction progresses, larger motor units are brought into play.
Trojan programs are most dangerous because they can create a back door. into your computer that gives malicious hackers direct access to your. system. Once installed, Trojans can hijack your PC and upload usernames, passwords, credit card numbers, social security numbers, and bank account.
Virus is the programming file.... A computer virus is a program that runs on your computer doing things you would not want it to do. Typically, this will involve doing dama â¦ ge to your hard drive, or sending mail without your permission. A virus gets on to your computer usually when you connect to the Internet. computer virus is a computer program that can copy itself  and infect a computer. The term virus is also commonly but  erroneously used to refer to other types of malwar â¦ e, including but  not limited to adware and spyware programs that do not have the  reproductive ability.